This is how you throw a change-up: you throw a change-up after throwing a Four-seam Fastball. It mixes up the batter because a change-up is a lot slower than a fastball. When the batter is geared up for a fastball you throw a change-up and the batter is way too early.
Type of Pitches
Fastballs: Four-seam Fastball, Two-seam Fastball, Splitter, Cutter, Sinker, Forkball
Off speed: Changeup, Palmball, Screwball,Knuckleball
Breaking Pitches: Curveball, Slurve, Slider